This invention relates to photonic devices in general, and more particularly to tunable filters and tunable lasers.
Tunable Fabry-Perot filters and tunable vertical cavity surface emitting lasers (VCSEL""s) have recently generated considerable interest in the art. This is because these devices are believed to have application for a wide range of different optical components and systems, e.g., wavelength division multiplexing (WDM) fiberoptic systems, switches, routers, highly compact spectroscopic interferometers, optical trans-receivers, etc.
In some tunable Fabry-Perot filters and in some tunable VCSEL""s, tuning is achieved by using an electrostatic field to move a top mirror relative to a bottom mirror, whereby to change the length of the Fabry-Perot cavity and hence tune the wavelength of the device.
While such a construction is advantageous in that it provides a fast and easy way to tune the device, in practice it has been found that the tuning range of the device is frequently limited by the electrostatic elements used to tune the device.
Accordingly, one object of the present invention is to provide an improved tunable Fabry-Perot filter.
Another object of the present invention is to provide an improved tunable VCSEL.
These and other objects are addressed by the present invention.
In one form of the invention, there is provided a tunable Fabry-Perot filter which comprises a bottom mirror mounted to the top of a substrate, a bottom electrode mounted to the top of the bottom mirror, a thin membrane support atop the bottom electrode, a top electrode fixed to the underside of the thin membrane support, a reinforcer fixed to the outside perimeter of the thin membrane support, and a confocal top mirror set atop the thin membrane support, with an air cavity being formed between the bottom mirror and the top mirror, wherein the top electrode and the bottom electrode are spaced further apart from one another than the top mirror is spaced from the bottom mirror.
In another form of the invention, there is provided a tunable VCSEL which comprises a bottom mirror mounted to the top of a substrate, a gain region mounted to the top of the bottom mirror, a bottom electrode mounted to the top of the gain region, a thin membrane support atop the bottom electrode, a top electrode fixed to the underside of the thin membrane support, a reinforcer fixed to the outside perimeter of the thin membrane support, and a confocal top mirror set atop the thin membrane support, with an air cavity being formed between the bottom mirror and the top mirror, wherein the top electrode and the bottom electrode are spaced further apart from one another than the top mirror is spaced from the bottom mirror.
And in another form of the invention, there is provided a tunable Fabry-Perot filter which comprises a bottom mirror mounted to the top of a substrate, a bottom electrode mounted to the top of the bottom mirror, a thin membrane support atop the bottom electrode, a top electrode fixed to the underside of the thin membrane support, a reinforcer fixed to the outside perimeter of the thin membrane support, and a confocal top mirror set atop the thin membrane support, with an air cavity being formed between the bottom mirror and the top mirror, wherein the top electrode and the bottom electrode extend toward one another.
And in another form of the invention, there is provided a tunable VCSEL which comprises a bottom mirror mounted to the top of a substrate, a gain region mounted to the top of the bottom mirror, a bottom electrode mounted to the top of the gain region, a thin membrane support atop the bottom electrode, a top electrode fixed to the underside of the thin membrane support, a reinforcer fixed to the outside perimeter of the thin membrane support, and a confocal top mirror set atop the thin membrane support, with an air cavity being formed between the bottom mirror and the top mirror, wherein the top electrode and the bottom electrode extend toward one another.